A 3 year old girl with a history of hydrocephalus is brought to the neurologist by her parents with a severe headache and fever. The girl underwent a revision of a ventriculoperitoneal shunt 1 month ago, and the neurologist suspects that an infection has occurred. Which of the following organisms would most likely be isolated from the shunt tubing?

Staphylococcal meningitis is fairly rare, occurring mostly in patients with indwelling ventriculoperitoneal shunts. Staphylococcus epidermidis, which normally colonizes the skin, is the most common organism causing this disorder; Staphylococcus aureus meningitis occasionally occurs. Bacteroides fragilis is a common cause of anaerobic infections, including sepsis and peritonitis, but it does not commonly cause meningitis. Diphtheroids (including Corynebacterium diphtheriae) are sometimes isolated from indwelling shunts, but in many cases they are simply contaminants, since some diphtheroids are normal skin flora. Escherichia coli is isolated from 30% to 50% of neonates with bacterial meningitis, but is not typically associated with shunt infections. Ref: Levinson W. (2012). Chapter 15. Gram-Positive Cocci. In W. Levinson (Ed),Review of Medical Microbiology & Immunology, 12e.